Pseudomonas aeruginosa colonization is an independent predictor of mortality in bronchiectasis patients. Non-CF bronchiectasis patients often experience symptom relief and improvement in lung function, however studies have failed to show significant improvement. Enhancing deposition of inhaled antibiotics and lung recruitment may improve the response to inhaled antibiotic treatment. Inhaling a low concentration of carbon dioxide (CO2) during antibiotic nebulization alters respiratory parameters. By changing these parameters one can try to alter the peripheral deposition of inhaled medication, which may improve treatment. SPECT/CT is the preferred technique to obtain information on deposition of inhaled drugs. However it is unknown if these measurements are feasible with inhalation of technetium DTPA (99mTc-DTPA) and tobramycin, due to the requirement of a relatively steady state uptake. This randomised cross-over proof of principle study investigates the feasibility of SPECT-CT scans in the evaluation of pulmonary deposition of Tobramycin. In addition, concomitant inhalation of CO2 enriched ambient air and the use of the breath-actuated mode of the AeroEclipse II nebulizer with adjusted Tobramycin dose are evaluated.